The invention relates to a closed cycle system which produces fuel for a chemical oxygen iodine laser (COIL) system. Particularly, the invention relates to the regeneration of lithium hypochlorite, which is used to generate singlet delta oxygen for use in a COIL apparatus.
The chemical oxygen-iodine laser (COIL) is a short wavelength high-power chemical laser with wide ranging industrial, technological, and military applications. The COIL produces a laser beam with a 1.315-xcexcm wavelength, which is well suited to a variety of uses. The COIL also has one of the best beam qualities of any available laser, which allows for clean cuts and welds, as well as simple beam correction and direction. In addition, the COIL laser has greater scalability than photolytic and solid state devices. COIL lasers, which are electronic transitional lasers, are favored over vibrational or rotational transition lasers because they have one of the best beam qualities of any available laser.
The COIL is powered by a fuel of molecular iodine and singlet delta oxygen (O2(1xcex94)). The singlet delta oxygen is an excited state of oxygen. When combined with iodine, the excited oxygen causes the iodine to dissociate rapidly. The oxygen and iodine are accelerated to a supersonic velocity through an expansion nozzle which creates a laser gain region. The dissociated iodine atoms release energy in the form of light within the laser gain region, thus powering the laser.
In a typical COIL laser, the singlet delta oxygen is produced through a two-step process, with the first step being the production of Basic Hydrogen Peroxide (BHP). BHP is an aqueous solution of H2O2 and MOH, where M represents an alkali metal such as lithium, sodium or potassium. BHP is generated by the combination of alkali hydroxide, typically potassium hydroxide, with hydrogen peroxide according to the formula:
OHxe2x88x92+H2O2+M+xe2x86x92O2Hxe2x88x92+H2O+M+xe2x80x83xe2x80x83(I)
Singlet delta oxygen (O2(1xcex94)) is then produced by reacting the perhydroxyl ions and alkali ions of the BHP with chlorine gas according to the formula:
Cl2+2O2Hxe2x88x92+2M+xe2x86x92H2O2+2MCl+O2(1xcex94)xe2x80x83xe2x80x83(II)
In this typical COIL system, a feed containing singlet delta oxygen is utilized as fuel for the laser until its readily usable quantities have been depleted. After being used in the lasing process, the remaining by-products of H2O2, KCl, KOH, and water are recycled to form fresh BHP.
Up to this point in time, COIL-type lasers have typically used BHP in the process described above to produce the singlet delta oxygen that is necessary to fuel the laser. There are two basic problems with this process. The first is that, in order to recycle the by-products of reaction (II) to make fresh BHP, a number of cumbersome, efficiency-reducing chemical steps, some of which are described above, are necessary. The second problem with the process is that BHP is unstable and corrosive. In light of these two problems, what is needed is a COIL system capable of producing singlet delta oxygen without using BHP. Further needed is a COIL system that converts laser waste products to laser fuels using only a few simple and efficient steps.
The invention is a method of utilizing lithium hypochlorite and hydrogen peroxide to generate singlet delta oxygen, which is used as fuel for a COIL device. The lithium hypochlorite is a much more stable reactant than BHP, resulting in safer singlet delta oxygen production than with previously known methods using BHP. The invention also comprises a method of regenerating lithium hypochlorite from the side products of singlet delta oxygen production. Such regeneration is simpler than the regeneration of BHP byproducts, potassium chloride and water, which makes the overall lithium hypochlorite cycle a more efficient alternative to the BHP based COIL devices of the past.
Singlet delta oxygen is produced according to the equation:
LiOCl+H2O2xe2x86x92LiCl+H2O+O2(1xcex94)xe2x80x83xe2x80x83(I)
where the hydrogen peroxide (H2O2) is preferably supplied as a vapor and the LiOCl is supplied as a LiOCl-rich LiOCl/LiCl aqueous solution. Water is removed from the LiCl-rich LiOCl/LiCl aqueous solution byproduct stream and the LiCl in the byproduct stream is regenerated under basic conditions according to the equations:
Li++Clxe2x88x92+2OHxe2x88x92xe2x86x92Li++OClxe2x88x92+H2O+2exe2x88x92xe2x80x83xe2x80x83(IIa)
and
H2O+xc2xdO2+2exe2x88x92xe2x86x922OHxe2x88x92xe2x80x83xe2x80x83(IIb)
The water that is removed from the byproduct stream is converted into hydrogen peroxide through a catalytic, electrochemical, or chemical process. Thus, the LiOCl based fuel cycle forms a true recycled laser fuel supply loop. Production of singlet delta oxygen is efficiently accomplished through use of the reaction of LiOCl with hydrogen peroxide.
An advantage of the process over prior processes of powering COIL lasers is that the invented system allows the production of the liquid components from the system by-products and residual liquids without any significant separation processes. The predominant separation processes are separation of water from solution. The water removal can be accomplished with a simple evaporation step, thereby increasing the efficiency of the process.